1993 300E M104 Failed Smog HCs & DTC Readings

[David C Klasse]

Okay, so it's been awhile since I've gotten a post out here to you guys... but I have a couple of independent mechanics that I've "accrued" throughout the years that help me out with this old car.

So I crashed my 2004 E500 in June... I was totally fine... but I had 217k miles on that car and she drove like a champ still! A/C wasn't working... and the transmission has just been rebuilt at 197k miles on the ORIGINAL tranny fluid... and I drove that baby HARD. And I digress....

So I decided I didn't want a car payment... so I bought a 1993 300E off craigslist for $1200 cash (did a cheaper version of carfax... clean title.. and had one owner at 107k miles in 2007).

Needless to say... I have pumped some dough into it! New brakes and pads all around... new water pump... and head gasket failure! Thankfully I got a steal and with parts, had it done for about $1400! This included new spark plugs and plug wires and a fan clutch. Additionally the head was machined... not sure how involved they got with the valves (I've heard this can be a smog issue)...

Okay, so the car drives GREAT! Needs a couple minor things such as some suspension components, a WORKING heater (AC works GREAT!), and a decent reverse gear would be nice!! Reverse works, but it's a B*TCH! I know I know, the B3 seal or whatever.

So my car fails smog miserably with a rating of 330 and 350 for the HydroCarbons (HC), max allowance is 250 and 280, respectively. BTW, this is in California.

So I have done some (quite a bit) of research and have deduced the high HC emissions due the catalytic converter, the egr valve, O2 sensor, vacuum leaks, smog/air pump, ignition COILs... and I think that' it (please tell me if I'm missing something)...

Ok, so I have a new O2 sensor that I'm having installed today... and I'm pretty sure that the cat would be making some rattling noises if It were going (wouldn't it!?).

THUS, I should read the codes, yeah!? As it turns out, when I purchased the vehicle, I didn't notice that the CHECK ENGINE bulb (AND SRS!) aren't there! So I'ms ure the MIL is on.

Moving right along... so I purchased the parts from radio shak (led, resistor, banana plugs, momentary push button) to assemble a DTC reader. As it turns out, my 16 plug deal HAS a Push Button (pin 2), AND an LED (pin 4), which lit up when I pressed it! So I'd like to read the codes... but can't find anywhere (even in the 169 pg PDF file by MBenz on reading the DTCs from 1988-98) that includes a built in LED and push button... I'm sure it's OEM...

In conclusion... what GIVES? I need to pass smog as the car isn't really even legally allowed to be driven and I already got the 30 day temp deal from the DMV. What do I do RE collecting the fault codes (# of flashes) from the built in "code reader" I'm sure I need to do something with the banana plugs... but WHAT, and WHERE?

PLEASE HELP!! Thanks guys! Nice to be back!!